Prob. with discharge or reset ?

Ron H

Joined Apr 14, 2005
7,014
<snip>But why would my proto board work perfect and reset instantly but not the PCB? This is confusing me! :confused: same parts same layout. LOL Thanks Jim
Did you read post 17? Are you sure the 555s have the same part number? All 555s are NOT equal.
 

Wendy

Joined Mar 24, 2008
22,208
The only problem I have with the CMOS theory is the LEDs. Of course, I've been wrong before. Though thinking about it, a standard 555 should be a minimum of 15KΩ, which is pretty close to the 10KΩ value.

Maybe not so far off base after all.
 

Ron H

Joined Apr 14, 2005
7,014
The only problem I have with the CMOS theory is the LEDs. Of course, I've been wrong before. Though thinking about it, a standard 555 should be a minimum of 15KΩ, which is pretty close to the 10KΩ value.

Maybe not so far off base after all.
I thought about the LEDs. They will approach an open circuit as the voltage across them drops. I don't know if that voltage is high enough prevent adequate discharge of C1 or not.
I already mentioned the 15k divider in post #14.
 
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